Abstract: Based on the flux chamber test model of the United States Environmental Protection Agency, an evaluation test method was established to assess the foam sealing performance. This study investigates the impact of expansion and foam thickness on the sealing performance of film-forming compressed air foam. The evaporation rate of oil vapor and the effective evaporation inhibition time were measured and calculated. Additionally, the main control mechanism of foam sealing performance was explained by analyzing the effects of expansion and the droplet dropping behavior of foam drainage. The results demonstrate that the film-forming compressed air foam can effectively inhibit the evaporation of 120# solvent oil vapor. Specifically, the effective inhibition time of 3 cm 6.5 times foam exceeds 30 minutes. It was observed that the sealing performance of compressed air foam increases as the expansion decreases. Therefore, it is recommended to use foam with an expansion of less than 15 times to address 120# solvent oil leakage accidents. Furthermore, for film-forming compressed air foam, the difference in oil vapor sealing performance due to different foaming ratios is small, and the liquid film within the foam layer is found to be the main factor controlling oil vapor volatilization. Notably, the foam with lower expansion contains a higher liquid content, resulting in a stronger inhibition effect on oil vapor volatilization.

Key words: expansion, foam thickness, suppression, oil-gas concentration